Electrical control apparatus



A. E. DODD ELECTRICAL CONTROL APPARATUS June 13, 1 944.

I Original Filed Dec. 23, 1941 fi s F "24 W 28, 20 M H125 ATTORNEY Patented June 13, 1944 ELECTRICAL CONTROL APPARATUS Arthur E. Dodd, Edgewood, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Original application December 23, 1941, Serial No. 424,151, now Patent No. 2,324,200, dated July 13, 1943.

Divided and this application November 11, 1942, Serial No. 465,183

Claims.

My invention relates to electrical control apparatus and particularly to apparatus for efiecting one function when a control circuit is energized by current of one relative polarity and another function when the control circuit is energized by current of the other relative polarity.

This application is a division of my application Serial No. 424,151, filed December 23, 1941, for Electrical control apparatus, now Patent No. 2,324,200 dated July 13, 1943.

In my application identified above there is shown control apparatus employing a polar relay and a biased polar relay energized from a polarized control circuit. The apparatus shown in that application is arranged so that in each position of the polar contacts of the polar relay, the winding of the polar relay is connected across the control wires through an asymmetric unit poled to permit flow of energy of a polarity efieotive to cause movement of the relay contacts to their other position. Ihe apparatus shown in that application is also arranged so that in each position of the polar contact of the polar relay the winding of the polar relay is connected across the control wires in series with the winding of a biased polar relay so that the biased polar relay checks correspondence between the position of the polar relay contacts and the polarity of the energy supplied to the control circuit.

In some situations a larger number of contacts are required than can be provided on a single biased polar relay.

An object of this application is to provide apparatus of the type shown in my original application but arranged so that the Winding of the polar relay is connected in series with one biased polar relay in one position of the polar relay contact and is connected in series with a different biased polar relay in the other position of the polar relay contact.

Other objects of the invention and features of novelty will be apparent from the following description taken in connection with the accompanying drawing.

I shall describe three forms of apparatus embodying my invention and shall then point out the novel features thereof in claims.

In the drawing, Fig. 1 is a diagram illustrating one embodiment of my invention, and

Figs. 2 and 3, are diagrams showing modifications of the invention adapted to indicate the position of a track switch and to check correspondence between a switch control relay and a switch indication relay.

Referring to Fig. 1 of the drawing, the reference character :P designates a polar relay, while the reference characters NA and NB designate auxiliary relays. The windings of the relays P, NA and NB are energized over a polarized control circuit here shown as comprising conductors It and H which are connected by contacts of a pole changer PC with a suitable source of direct current, such as a battery, the terminals of which are designated and The conductors l0 and II may be line wires, or they may be the track rails of a section of railway track, while the pole changer PC may be a manually operated device, it may be the contacts of a relay, or it may be any other suitable mechanism.

The relay P has associated therewith a rectifier unit consisting of rectifier elements .KI and K2 which are connected in series and are both poled to permit energy to flow in the same direction.

The auxiliary relays NA and NB are preferably, but not necessarily, of the biased polar type, and each is arranged so that its contacts become picked up only when the positive terminal of the source is connected to the left-hand or first terminal of the relay winding. One form of relay which may be employed for this purpose is shown in Letters Patent of the United States No. 2,057,605 granted October 13, 1936 to Herman G. Blosser.

The relay P is of the polar stick type being constructed in such manner that the relay contacts when moved to either position remain in that position until energy of the polarity effective to move the relay contacts to their other position is supplied to the relay winding.

The equipment is shown in the condition it assumes when energy of normal polarity is supplied to the control wires [0 and II, and the contacts l3 and It of polar relay P are in their lefthand or normal positions. At this time energy flows from the positive terminal of the source through control wire I I, winding of relay P, and contact M to the left-hand or first terminal of the rectifier unit and also to the left-hand or first terminal of the winding of relay NA, through this winding, contact l3 of relay P, and control wire ID to the negative terminal of the source. Accordingly, the contact ISA of relay Na is picked up, while the circuit of relay NB is interrupted and thecontact I5B is released. The contacts I5A and 15B may be employed in any desired manner for any appropriate purpose.

On movement of the contacts of the pole changor PC the supply of energy to the relay NA is interrupted and the relay contacts release.

When the contacts of the pole changer are moved to their reverse positions the positive terminal of the source is connected to control wire ill, and energy flows from this wire through rectifier Kl', contact 14, winding of relay P, and

terminal of the winding of relay NB, through,

this winding, contact I4 of relay P, winding of relay P, and control wire II to the negative terminal of the source. The energy in the winding of relay NB, therefore, flows in the proper direction to pick up the relay contact, while the env ergy in the winding of relay P is effective to maintain the contacts l3 and I4 in their righthand or reverse positions.

On subsequent movement of the contacts of the pole changer PC away from their reverse positions the supply of energy to the winding of relay N13 is interrupted and the relay contacts release} V p -Whe n the contacts of the pole changer PC are movedto their normal positions energy of normal polarityis supplied to the relay P over the circuit which is traced from the positive terminal of the source through control wire II, winding of relay P, right-hand or reverse contact l4, rectifier K2, and control wire ID to the negative terminalof the source. ,This energy causes the contacts of the relay P, to move to their normal or left-hand positions while when the contacts |3 and M are in their normal positions the windings of relays Pgand NA are energized in series over the circuit traced above so that the contact I 5A of relay NA is picked up.

' If the supply of energy over the control wires is interrupted the contacts of both relays NA and NB will be released. V

In the system shown in Fig. 1 the rectifiers KI and K2 prevent energization of the relays NA and NB by current of the wrong polarity, while the system operates to check the circuits of the rectifiers to see that these circuits are intact.

If desired the relays NA and NB may each have a, rectifier, not shown, connected across its terminals as shown in Fig. 3 to increase the release period of the relay, and to provide increased protection against energization of the relay by energy of the wrong polarity.

The. system shown in Fig. l of the drawing is adapted foruse in a switchindication circuit to indicate theposition of a track switch and to also indicate when the switch. control relay and the switch indication relay associated with a railway trackswitch are in correspondence, and Fig. 2 is a diagram showing this application of the invention. r.

. Referring to'Fig. 2 there is shown therein a track switch W which is movable between a normal and a reverse position by a switch machine SM.. The machine SM may be of any appropriate construction and is controlled by a polarized switchcontrol relay WR, which in turn is controlled, by .a control lever L. The switch has associated therewith contacts 2|) and 2| which are governed in accordance with the position of the switch, and control the supply of energy to the relay. P and to the auxiliary relays NA and NB, while the circuits of these relays are controlled loy neutral and polar contacts of relay W R. The system shown in Fig. 2 employs a rectifier ,unit similar to that shown in Fig. 1 and consisting of rectifier elements KI and K2.

The equipment is shown in the condition which Source.

it assumes when the control lever L and the switch W are in their normal positions. As 1ever L is in its normal position energy of normal polarity is supplied to the relay WR and its neutral contact 2 1 is picked up, while its polar contact 25 is in its left-hand or normal position so that a circuit for the switch machine SM is established to cause the switch W to be moved to its normal position and to be maintained there.

As the switch W is in its normal position the contact 20 establishes connection from the positive terminal of a source to indication wire 26, while contact 2| establishes connection from the negative terminal of the source to indication wire 28 with the result that energy of normal polarity is supplied to the wires 26 and 28. As the contact I4 of relay P is in its normal or left-hand position, and as the polar contact 30 of relay WR is in its left-hand or normal position and the neutral contact 3| of relay WR, is picked up, the relays P and NA are energized in series over the circuit which is traced from the positive terminal of the source through contact 20, wire 26, winding of relay P, contact l4, and Wire 33 to the first terminal of the rectifier unit, winding of relay NA, contacts 30 and 3| of relay WR to the intermediate terminal of the rectifier unit, wire 28, and contact 2| to the negative terminal of the source. The positive terminal of the source is connected to the left-hand or first terminal of the winding of relay NA so that the direction of flow of energy in this winding is proper to pick up the relay contact I5A, and this contact is picked up and may establish a circuit to permit clearing of. signals appropriate for movement of trafiic in the normal position of the switch.

When the lever L is moved to its reverse position energy of reverse polarity'is supplied to the relay WR- and its polar contacts 25 and 35 move to their right-hand or reverse positions.

On this movement of contact 25 a circuit for the switch machine SM is established to cause this machine to move the switch to its reverse position, while on this movement of contact 30 the circuit traced above for energizing the relay NA is interrupted.

When the switch W completes its movement to its reverse position contact 20 connects the positive terminal of the sounce to wire 28 and contact 2| connects the negative terminal of the source to wire 26 with the result that energy "is supplied to relay P over the circuit which is traced from the positive terminal of the source over wire 28, through rectified KI, wire 33, normal polar contact I4, winding of relay P, and control wire 26 to the negative terminal of the This energy causes the contact of relay P to move to its right-hand or reverse position, and when this contact is in this position the windings of relays P and NB are energized in series over the circuit which is traced from the positive terminal of the source through contact 28, and wire 28 to the intermediate terminal of the rectifier unit, and contacts 3| and 30 of relay WR to the left-hand or first terminal of the winding of relay NB, through this Winding to the second terminal of the rectifier unit, wire 34, right-hand contact I4, winding of relay P, wire 26, and contact 2| to the negative terminal of the source. As energy flows through the Winding of relay NB from its left-hand or first terminal to its right-hand or second terminal this energy is effective to pick up the contact |5B of the relay. This contact may establish a circuit to permit clearing of signals appropriate when the switch is in its reverse position.

On subsequent movement of the switch control lever L to its normal position energy of normal polarity is supplied to the, relay WR and its contacts 25- and 3!! shift to their left-hand or normal positions. On this movement of contact 25 the circuit for causing the switch machine SM to move the switch from its reverse to its normal position is established, while on this movement of contact 30 the circuit of the relay NB is interrupted.

When the switch W completes its movement to its normal position the contacts 20 and 2! establish the circuit to supply energy of normal polarity to the wires 26 and 28, and the relay P is energized over the circuit which is traced from the positive terminal of the source through contact 20, wire 26, winding of relay P, righthand polar contact I4 of relay P, wire 34, rectifier K2, wire 28, and contact 2| to the negative terminal of the source. This energy causes the contact It to shift to its left-hand or normal position, and when the contact is in this position the relays P and NA are energized in series over the circuit traced above.

The system provided by this modification is arranged so that if the contacts of the switch control relay WR and of the relay P are out of correspondence the relays NA and NB will both be released, while these relays will also be released if the energy supplied to the wires 26 and 28 is not of the proper polarity.

The system provided by this modification is also arranged so that continuity of the circuits through the rectifiers is checked so that failure of the rectifiers will be promptly detected.

The modification shown in Fig. 2 is arranged so that interruption of the supply of energy to the wires 26 and 28 for any reason, such as failure of the switch to complete its movement, will result in deenergization of both of the relays NA and NB. In addition, this modification is arranged so that when the switch control relay WE is deenergized its neutral contact 31 is released and prevents energization of relay NA or NB.

In Fig. 3 of the drawing there is shown another moclification of the invention which may be employed to indicate correspondence between a switch control relay and a switch indication relay.

The modification shown in Fig. 3 employs auxiliary relays NA and NB, while it employs a rectifier unit consisting of rectifier elements K5 and K6 which are connected in series and are both poled to permit energy to how from the right-hand or second terminal of the unit to the left-hand or first terminal of the unit.

The equipment of Fig. 3 is shown in the condition which it assumes when switch control lever L is in its normal position, the contacts of switch control relay WR and switch indication relay P are in their normal positions, and the switch W is in its normal position.

As the switch W is in its normal position the switch operated contacts 28 and 2| supply energy of normal polarity to the indication wires 26 and 28 so that relays P and NA are energized by current supplied over the circuit which is traced from the positive terminal of the source through contact 20, wire 26, winding of relay P, and left-hand contact [4 of relay P to the left-hand or first terminal of the rectifier unit, front neutral contact 3| and left-hand polar contact 30 of relay WR to the left-hand or first i terminal of the winding of relayiNA, through the Winding of relay NA, left-hand contact 36 of relay P to the right-hand or second terminal of the rectifier unit, through rectifier K5, wire 28, and contact 2| to the negative terminal of the source. Accordingly, contact I5A of relay NA is picked up.

On movement of the control lever L to its ,re- Verse position energy Of reverse polarity is supplied to the switch control relay WR and its polar contacts shift to their right-hand or reverse positions with the result that contact 25 establishes the circuit to cause the switch machine SM to move the switch W to its reverse position.

In addition, at this time contact 300i relay WR interrupts the circuit traced above for'energizing the relay NA and the contacts of this relay release.

When the switch W is moved to its reverse p0- siti'on contacts and 2| cause energy of reverse polarity to be supplied to wires and 28. and energy is supplied to relay P over the circuit which is traced from the positive terminal of the source through contact 20, wire 28, rectifier K6, left-hand polar contact M of relay P, winding of relay P, wire 25, and contact 2! to the negative terminal of the source.

The energy supplied to the relay P over this circuit causes the contacts of the relay to shift to their right-hand or reverse positions so that the circuit traced above is interrupted, and a circuit is established to energize the relay P and NE .in series. This circuit is traced from the positive terminal of the source through contact 20, wire 28, rectifier K5, front neutral contact 3|v and right-hand polar contact of relay WR to the right-hand or first terminal of the winding of relay NB, through this winding, right-hand contacts 36 and I4 of relay P, winding of relay P, wire 26, and Contact?! to the negative terminal of the source. In this modification the relay NB is arranged so that its contact becomes picked up only when energy flows through the relay winding from the right-hand terminal to the lef hand terminal thereof. It will be seen that the direction of flow of energy through the winding of relay NE at thi time is proper to pick up the relay contacts, and accordingly, the contact I513 picks up, and may establish a circuit to permit clearing of a signal appropriate for the reverse position of the switch.

On a subsequent movement of the control lever L to its normal position the contacts of the relay WR shift to their left-hand or normal positions so that contact 25 establishes the circuit to cause the switch machine SM to move the switch W to its normal position.

In addition, at this time contact 38 of relay WR interrupts the circuit traced above for energizing the relay NB and the contacts of this relay release.

When the switch W completes its movement to its normal position the switch operated contacts 20 and 2! establish connections to supply energy of normal polarity to the indication wires 26 and 28 and this energy is supplied to the relay P over the circuit which is traced from the positive terminal of the source through contact 20, wire 26, winding of relay P, right-hand contact 14 of relay P, rectifier K5, wire 28, and contact 2| to the negative terminal of the source.

The energy supplied to the relay P causes the contacts of this relay to shift to their left-hand or normal positions, and when the relay contacts are in this position they establish the circuit traced above to energize the relays NA and P in series. I

The system provided by this modification of the invention is arranged so that the integrity of the rectifiers K5 and K6 is checked and failure of either of these rectifiers will be promptly detected. This modification is also arranged so that the relays NA and NB cannot be energized if the contact of relay WR and P are out of correspondence, while rectifiers K1 and K8 may be connected across the terminals of the relays NA and NB to prevent energization of these relays, if energy of the wrong polarity is supplied to the indication wires.

Although I have herein shown and described several forms of electrical control apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention. 7

Having thus described my invention, what I claim is:

1. In combination, a control circuit comprising a first and. a second conductor to which energy of one polarity is supplied at times and to which energy of the other polarity is supplied at other times. a polar relay connected in series with one of said conductors and having a contact movable to one position or another according as energy of one polarity or the other is supplied to the relay winding, a rectifier unit comprising a first and a second rectifier element connected in series between a first and a second terminal and both poled to permit energy to flow from said second to said first terminal, said unit also having an 1ntermediate terminal between said rectifier elements, the first conductor being connected to the intermediate terminal of said rectifier unit, the contact of said polar relay being efiective when in the position which it occupies when the positive l terminal of the source is connected to the first conductor to connect said second conductor to the second terminal of said rectifier unit and being efiective when in the position which it occupies when the positive terminal of the source is connected to the second conductor to connect said second conductor to the first terminal of said rectifier unit, a first and a second auxiliary relay, means for connecting one terminal of the winding of the first auxiliary'relay to the firstterminal of the rectifier unit and for connecting the other terminal of the winding of said first auxiliary relay to the intermediate terminal of said rectifier unit, means for connecting one terminal of the winding of the second auxiliary relay to the intermediate terminal of said rectifier unit and for connecting the other terminal of the winding of the second auxiliary relay to the second terminal of said rectifier unit, a circuit controlled by a contact of said first auxiliary relay, and a circuit controlled by a contact of said second auxiliary relay.

2. In combination, a control circuit comprising a first and a second conductor to which energy of one polarity is supplied at times and to which energy of the other polarity is supplied at other times, a polar relay connected in series with one of said conductors and having a contact movable to one position or another according as energy of one polarity or the other is supplied to the relay winding, a rectifier unit comprising a first and a second rectifier element connected in series between a first and a second terminal and both poled to permit energy to flow from said second to said first terminaLsaid unit also having an intermediate terminal between said rectifier elements, the first conductor being connected to the intermediate terminal of said rectifier unit, the contact of said polar relay being efiective when in the position which it occupies when the positive terminal of the source is connected to the first conductor to connect said second conductor to the second terminal of said rectifier unit and being effective when in the position which it occupies when the positive terminal of the source is connected to the second conductor to connect said second conductor to the first terminal of said rectifier unit, a first and a second auxiliary relay each having a winding having a first and a second terminal and each having a normally released contact which becomes picked up only when energy flows through the relay winding from the first to the second terminal thereof, means for connecting the first terminal of the winding of the first auxiliary relay to the first terminal of said rectifier unit and for connecting the second terminal of the winding of said first auxiliary relay to one of the other terminals of said rectifier unit, means :for connecting the second terminal of the winding of the second auxiliary relay to the second terminal of said rectifier unit and for connecting the first terminal of the winding of said second auxiliary relay to one of the other terminals of said rectifier unit. a circuit controlled by a contact of said first auxiliary relay, and a circuit controlled by a contact of said second auxiliary relay.

3. In combination, a railway track switch, a machine for moving said switch between a nor mal and a reverse position, a polarized switch control relay to which energy of normal polarity 1s supplied at times and to which energy of reverse polarity is supplied at other times, said relay having polar contacts effective when in their normal position to cause the switch machine to move the switch to its normal position and effective when in their reverse position to cause the switch machine to move the switch to its reverse position, an indication circuit comprising a first and a second conductor, means effective when the switch is in its normal position to supply to the indication circuit energy of a polarity in which the positive terminal of the source is connected to one of said conductors and eifectwo when the switch is in its reverse position to supply to the indication circuit energy of a polarity in which the positive terminal of the source is connected to the other of said conductors, a rectifier unit comprising a pair of rectifier elements connected in series between a first and a second terminal and both poled to permit energy to fio-w from the second to the first terminal, said unit also having an intermediate terminal between said rectifier elements, a polar ndication relay having its winding connected 111 series with one of said indication conductors, one of said indication conductors being connected to the intermediate terminal of the rectifier unit, a contact of the polar indication relay being effective according as it is in one or the other of its positions to connect the other indication conductor to the first or second terminal of said rectifier unit, the equipment being arranged so that the polar indication relay contact connects said other conductor to the first or second terminal of the rectifier unit according as said contact is in the position to which it is moved when the relay is energized by current of the polarity in which the negative or the positive terminal of the source is connected to said' one indication conductor, a first and a second auxiliary relay, means for connecting one terminal of the winding of the first auxiliary relay to the terminal of the rec tifier unit to which the indication relay contact establishes connection when the relay is energized by current of the polarity which is supplied thereto when the switch is in its normal position, means for connecting the other terminal of the winding of the first auxiliary relay to one of' the other terminals of the rectifier unit, means for connectingone terminal of the winding of the second auxiliary relay to the terminal of the rectifier unit to which the indication relay contact establishes connection when the relay is energized by current of the polarity which is supplied thereto when the switch is in its reverse position, means for connecting the other terminal of the second auxiliary relay to one of the other terminals of said rectifier unit, the circuits of the auxiliary relays being controlled by the polar contacts of the switch control relay so that the circuit of the first auxiliary relay is complete only when said polar contacts are in their normal position and so that the circuit of the second auxiliary relay is complete only when said polar contacts are in their reverse position, a circuit controlled by a contact of the first auxiliary relay,'and a circuit controlled by a contact of the second auxiliary relay.

4. In combination, a railway track switch, a machine for moving said switch between a normal and a reverse position, a polarized switch control relay to which energy of normal polarity is supplied at times and to which energy of reverse polarity is supplied at other times, said relay having polar contacts effective when in their normal position to cause the switch machine to move the switch to its normal position and effective when in their reverse position to cause the switch machine to move the switch to its reverse position, an indication circuit comprising a first and a second conductor, means effective when the switch is in its normal position to supply to the indication circuit energy of a polarity in which the positive terminal of the source is connected to one of said conductors and efie ctive when the switch is in its reverse position'to supply to the indication circuit energy of a polarity in which the positive terminal of the source is connected to the other of said conductors, a rectifier unit comprising a pair of rectifier elements connected in series between a first and a second terminal and both poled to permit energy to fiow from the second to the first terminal, said unit also having an intermediate terminal between said rectifier ele ments, a polar indication relay having its winding connected in series with one of said indication conductors, one of said indication conductors being connected to the intermediate terminal of the rectifier unit, a contact of the polar indication relay being effective according as it is in one or the other of its positions to connect the other indication conductor to the first or second terminal of said rectifier unit, the equipment being arranged so that'the polar indication relay contact connects said other conductor to the first'or second terminal of the rectifier unit according as said contact is in the position to which it is moved when the relay is energized by current of the polarityin which the negative or the positive terminal-of the source is connected to said one indication conductor, a first auxiliary relay having one terminal of its winding connected to the first terminal of said rectifier unit and a second auxiliary relay having one terminal of its winding connected to the second terminal of said rectifier unit, and means effective according as the polar contacts of the switch control relay are in theirnormal or reverse position to connect the intermediate terminal of said rectifier unit to the other terminal of the first or the second auxiliary relay.

5. In combination, a pair of conductors to which energy of normal polarity is supplied at times and to which energy ofreverse polarity is supplied at other times, a polar relay having one terminal of its winding connected to oneof said conductors, means including a normal polar contact of said polar relay for connecting the other terminal of the winding of said relay to said other conductor through a first asymmetric unit poled to permit flow of energy of reverse polarity and to also connect said other terminal of said polar relay winding to said other conductor in series with the winding of a first auxiliary relay, and means including a reverse polar contact of said polar relay for connecting the other terminal of the winding of said polar relay to said other conductor through a second asymmetric unit poled to permit fiow of current of normal polarity and to also connect said other terminal of said polar relay winding to said other conductor in series with thewinding of a second auxiliary relay.

6. In combination, a railway track switch, a machine for moving said switch between a normal and a reverse position, a polarized switch control relay to which energy of normal polarity is supplied at times and to which energy of reverse polarity is supplied at other times, said relay having polar contacts effective when in their normal position to cause the switch machine to move the switch to its normal position and effective when in their reverse position to cause the switch machine to move the switch to its reverse position, a 'pair of indication conductors, means effective according as the switch is in its normal or its reverse position to supply to said indication conductors energy of normal or reverse polarity, a polar indication relay-having one terminal of its winding connected to one of said indication conductors, means including a normal polar contact of said indication relay for connecting the other terminal of the winding of said indication relay to the other one of said indication conductors through an asymmetric unit poled to permit flow ofv ener of -reverse polarity, means including a reverse polar contact of said indication relay for connecting the other terminal of the winding of said indication relay to the other one of-said indication conductors through an asymmetric unit poled to permit flow of energy of normal polarity, means, including a normal polar contact of. said indication relay and a normal polar contact of said control relay for connecting said other terminal ofthe winding of said indication relay to said other indication conductor in series with the winding of a first auxiliary relay, means including a reverse polar contact of said indication relay and areverse polar contact of said control relay for connecting said'oth'er terminal of the winding of said indication relay to said otherindication conductor in series with the winding of asecond auxiliary relay, a circuit controlled'byflafcontact of said first auxiliary relay, and a circuit controlled by a contact of said second auxiliary relay.

7. In combination, a railway track switch, a machine for moving said switch between a normal and a reverse position, a polarized switch control relay to which energy of normal polarity is supplied at times and to which energy of reverse polarity is supplied at other times, said relay having polar contacts effective when in their normal position to cause the switch machine to move the switch to its normal position and effective when in their reverse position to cause the switch machine to move the switch to its reverse position, a pair of indication conductors, means effective according as the switch is in its normal or its reverse position to supply to said indication conductors energy of normal or reverse polarity, a polar indication relay having one terminal of its winding connected to one of said indication conductors, means including a normal polar contact of said indication relay for connecting the other terminal of the winding of said indication relay to the other one of said indication conductors through a first asymmetric unit poled to permit flow of energy of reverse polarity, means including a reverse polar contact of said indication relay for connecting the other terminal of the winding of said indication relay to the other one of said indication conductors through a second asymmetric unit poled to permit fiow of energy of normal polarity, means including a normal polar contact of said control relay for connecting a first auxiliary relay in multiple with said first asymmetric unit, means including a reverse polar contact of said control relay for connecting a second auxiliary relay in multiple with said second asymmetric unit, a circuit controlled by said first auxiliary relay, and a circuit controlled by said second auxiliary rela 8. In combination, a railway track switch, a machine for moving said switch between a normal and a reverse position, a polarized switch control relay to which energy of normal polarity is supplied at times and to which energy of re verse polarity is supplied at other times, said relay having polar contacts effective when in their normal position to cause the switch machine to move the switch to its normal position and effective when in their reverse position to cause the switch machine to move the switch to its reverse position, a pair of indication conductors, means effective according as the switch is in its normal or its reverse position to supply to said indication conductors energy of normal or reverse polarity a polar indication relay having one terminal of its winding connected to one of said indication conductors, means including a polar contact of said indication relay for connecting the other terminal of the winding of said indication relay to the other one of said indication conductors through a first asymmetric unit poled to permit flow of energy of reverse polarity, means including a reverse polar contact; of said indication relay for connecting the other terminal of the winding of said indication relay to the other one of said indication conductors through a second asymmetric unit poled'to permit fiow of energy of normal polarity, means including normal polar contacts of said indication relay and of said control relay for connecting the winding of a first auxiliary relay in series with said second asymmetric unit and in multiple with said first asymmetric unit, means including reverse polar contacts of said indication relay and of said control relay for connecting the winding of a second auxiliary relay in series with said first asymmetric unit and in multiple with said second asymmetric unit, a circuit controlled by said first auxiliary relay, and a circuit controlled by a contact of said second auxiliary relay.

9. In combination, a pair of conductors to which energy of normal polarity is supplied at times and to which energy of reverse polarity is supplied at other times, a polar relay having one terminal of its winding connected to one of said conductors, means including a first normal polar contact of said relay for connecting the other terminal of the winding of said relay to the other conductor through a first asymmetric unit poled to permit flow of energy of reverse polarity, means including a first reverse polar contact of said relay for connecting the other terminal of said relay to said other conductor through a second asymmetric unit poled to permit flow of energy of normal polarity, means including a second normal polar contact of said relay for connecting the other terminal of the winding of said relay to said other conductor in series with the winding of a first auxiliary relay, means including a second reverse polar contact of said polar relay for connecting the other terminal of the winding of said polar relay to said'other conductor in series with the winding of a second auxiliary relay, a circuit controlled by a contact of said first auxiliary relay, and a circuit controlled by a contact of said second auxiliary relay.

10. In combination, a railway track switch, a machine for moving said switch between a normal and a reverse position, a polarized switch control relay to which energy of normal polarity is supplied at times and to which energy of reverse polarity is supplied at other times, said relay liaving polar contacts effective when in their normal position to cause the switch machine to move the switch to its normal position and effective when in their reverse position to cause the switch machine to move the switch to its reverse position, a pair of indication conductors, means eiiective according as the switch is in its normal or its reverse position to supply to said indication conductors energy of normal or reverse polarity, a polar indication relay having one terminal of its winding connected to one of said indication conductors, means including a normal polar contact of said indication relay for finnecting the other terminal of thewinding of said indication relay to the other one of said indication conductors through a first asymmetric unit poled to permit flow of energy of reverse polarity, means including said normal polar contact of said indication relay andia normalpolar contact of said control relay for also connecting the other terminal of the Winding of said indication relay to the other one of said indication conductors in series with the winding of a firstauxiliary relay, means including a reverse polar contact of said indication relay for connecting the other terminal of the winding of said indication relay to the other one of said indication conductors through a second asymmetric unit poled to permit flow of energy of normal polarity, means including said reverse polar contact of saidindication relay and a reverse polar contact of said control relay for also connecting the other terminal of the winding of said indication relay to the other one of said indication conductors in series with the winding of a second auxiliary relay, a circuit controlled by said first auxiliary relay, and a circuit controlled by said second auxiliary relay.

' r i 7 ARTHUR- E. .DODD. 

